The present invention relates generally to field devices for use in industrial processes. In particular, this invention relates to a seal board for a field device such as an industrial process pressure transmitter.
Pressure transmitters may be mounted near a process and may be used to measure a fluid pressure related to an industrial process. Pressure transmitters can also be used to indirectly measure other parameters, such as velocity, fluid height, altitude, and fluid flow. The measured process fluid pressure can be sent to a host computer, a controller or other devices to ensure that the industrial process is monitored and controlled.
Some pressure transmitters have enclosures that are divided into two compartments, a terminal block compartment for terminal block components and an electronics compartment for active electronic assemblies (feature boards) separated by a bulkhead. The terminal block compartment allows a user access to electrical connections at the terminal block, while the electronics compartment protects the feature board(s) from the surrounding environment. Signals from one compartment are passed through the bulkhead to the other compartment. There is a need to electrically isolate the signals and limit any outside electronic noise (EMI) from entering the electronics compartment while still providing an environmental seal between the two compartments. In particular, a cost effective method is desired to pass higher numbers (i.e., a higher density) of individual electrical signals through the bulkhead while still providing electrical isolation from one another and the housing seal. One current technique for reducing EMI noise uses a complex stamped brazed radio frequency interference (RFI) filter tub assembly using metal stamping, ceramic filter bodies, and epoxy potting. This stamped brazed RFI filter tub assembly is difficult and costly to manufacture. Another alternative uses individual screw-in filter assemblies.